Magnetic tape servo format allowing for increased linear tape density and systems thereof

ABSTRACT

In one general embodiment, a magnetic recording tape includes a plurality of servo tracks, each servo track comprising a series of magnetically defined bars, wherein an average stripe width of the bars is between about 1.0 micron and about 2.2 microns, where an average servo frame length of groups of the bars comprising a servo frame is between about 120 microns and about 180 microns. In another general embodiment, a system includes a head having at least one servo reader and an array of data transducers of a type selected from a group consisting of readers and writers; and a controller operative to selectively enable every other transducer of a particular type in the array in a first mode of operation, and operative to selectively enable every transducer of the particular type in the array in a second mode of operation.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/691,604 filed Jan. 21, 2010, and which is herein incorporated byreference.

BACKGROUND

As tape capacity increases with each generation, smaller and smallertrack spacing is being demanded along with tighter Track MisRegistration(TMR) requirements and increased linear density such that tape capacitycan be effectively increased without an accompanying loss in dataintegrity.

As this occurs, the Tape Dimensional Stability (TDS) of the tape mediumitself becomes more of a factor in the TMR budget. This TDS factor canbe mitigated by improving the media properties, e.g., controlling thetemperature, humidity, and tension environments, and by minimizing theoverall track spacing as written by the head in a single pass.

Therefore, a magnetic tape with reduced overall track spacing thatmitigates the TDS factor would be beneficial to the field of magnetictapes and magnetic tape data writing and/or reading.

SUMMARY

A magnetic recording tape according to one embodiment includes aplurality of servo tracks, each servo track comprising a series ofmagnetically defined bars, wherein an average stripe width of the barsis between about 1.0 micron and about 2.2 microns, where an averageservo frame length of groups of the bars comprising a servo frame isbetween about 120 microns and about 180 microns.

A system according to one embodiment includes a head having at least oneservo reader and an array of data transducers of a type selected from agroup consisting of readers and writers; and a controller operative toselectively enable every other transducer of a particular type in thearray in a first mode of operation, and operative to selectively enableevery transducer of the particular type in the array in a second mode ofoperation.

A method for writing and/or reading data on a magnetic tape, accordingto one embodiment, includes reading at least one of a plurality of servotracks on the magnetic tape, the servo tracks each comprising a set ofmagnetically defined bars, the magnetically defined bars having: anaverage stripe width of the bars of between about 1.0 micron and about2.2 microns; and an average servo frame length of groups of the barscomprising a servo frame of between about 120 microns and about 180microns.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a network architecture, in accordance with oneembodiment.

FIG. 2 shows a representative hardware environment that may beassociated with the servers and/or clients of FIG. 1, in accordance withone embodiment.

FIG. 3 depicts a simplified schematic diagram of a magnetic head, servopatterns, and magnetic tape, according to one embodiment.

FIG. 4 depicts a simplified schematic diagram of magnetic head and servopattern according to one embodiment.

FIG. 5 depicts a simplified schematic diagram of magnetic head and servopattern according to one embodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

In one general embodiment, a magnetic recording tape includes aplurality of servo tracks, each servo track comprising a series ofmagnetically defined bars, wherein an average stripe width of the barsis between about 1.0 micron and about 2.2 microns, where an averageservo frame length of groups of the bars comprising a servo frame isbetween about 120 microns and about 180 microns.

In another general embodiment, a system includes a head having at leastone servo reader and an array of data transducers of a type selectedfrom a group consisting of readers and writers; and a controlleroperative to selectively enable every other transducer of a particulartype in the array in a first mode of operation, and operative toselectively enable every transducer of the particular type in the arrayin a second mode of operation.

In yet another general embodiment, a method for writing and/or readingdata on a magnetic tape includes reading at least one of a plurality ofservo tracks on the magnetic tape, the servo tracks each comprising aset of magnetically defined bars, the magnetically defined bars having:an average stripe width of the bars of between about 1.0 micron andabout 2.2 microns; and an average servo frame length of groups of thebars comprising a servo frame of between about 120 microns and about 180microns.

As will be appreciated by one skilled in the art, the present inventionmay be embodied as a system, method or computer program product.Accordingly, the present invention may take the form of an entirelyhardware embodiment, a software embodiment (including firmware, residentsoftware, micro-code, etc.) operating an apparatus or an embodimentcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module” or “system.” Furthermore,the present invention may take the form of a computer program productstored in any tangible medium of expression having computer-usableprogram code stored in the medium.

Any combination of one or more computer usable or computer readablemedium(s) may be utilized. The computer-usable or computer-readablemedium may be, for example but not limited to, an electronic, magnetic,optical, electromagnetic, infrared, or semiconductor system, apparatus,or device. More specific examples (a non-exhaustive list) of thecomputer-readable medium would include the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a portable compact disc read-only memory (CD-ROM), anoptical storage device, or a magnetic storage device.

Computer program code for carrying out operations of the presentinvention may be written in any combination of one or more programminglanguages, including an object oriented programming language such asJava, Smalltalk, C++ or the like and conventional procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The program code may execute entirely on the user's computer,partly on the user's computer, as a stand-alone software package, partlyon the user's computer and partly on a remote computer or entirely onthe remote computer or server. In the latter scenario, the remotecomputer may be connected to the user's computer through any type ofnetwork, including a local area network (LAN) or a wide area network(WAN), or the connection may be made to an external computer (forexample, through the Internet using an Internet Service Provider).

The present invention is described herein with reference to flowchartillustrations and/or block diagrams of methods, apparatus (systems) andcomputer program products according to embodiments of the invention. Itwill be understood that each block of the flowchart illustrations and/orblock diagrams, and combinations of blocks in the flowchartillustrations and/or block diagrams, can be implemented by computerprogram instructions. These computer program instructions may beprovided to a processor of a general purpose computer, special purposecomputer, or other programmable data processing apparatus to produce amachine, such that the instructions, which execute via the processor ofthe computer or other programmable data processing apparatus, createmeans for implementing the functions/acts specified in the flowchartand/or block diagram block or blocks.

These computer program instructions may also be stored in acomputer-readable medium that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablemedium produce an article of manufacture including instruction meanswhich implement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer orother programmable data processing apparatus to cause a series ofoperational steps to be performed on the computer or other programmableapparatus to produce a computer implemented process such that theinstructions which execute on the computer or other programmableapparatus provide processes for implementing the functions/actsspecified in the flowchart and/or block diagram block or blocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

FIG. 1 illustrates a network architecture 100, in accordance with oneembodiment. As shown in FIG. 1, a plurality of remote networks 102 areprovided including a first remote network 104 and a second remotenetwork 106. A gateway 101 may be coupled between the remote networks102 and a proximate network 108. In the context of the present networkarchitecture 100, the networks 104, 106 may each take any formincluding, but not limited to a LAN, a WAN such as the Internet, PSTN,internal telephone network, etc.

In use, the gateway 101 serves as an entrance point from the remotenetworks 102 to the proximate network 108. As such, the gateway 101 mayfunction as a router, which is capable of directing a given packet ofdata that arrives at the gateway 101, and a switch, which furnishes theactual path in and out of the gateway 101 for a given packet.

Further included is at least one data server 114 coupled to theproximate network 108, and which is accessible from the remote networks102 via the gateway 101. It should be noted that the data server(s) 114may include any type of computing device/groupware. Coupled to each dataserver 114 is a plurality of user devices 116. Such user devices 116 mayinclude a desktop computer, lap-top computer, hand-held computer,printer or any other type of logic. It should be noted that a userdevice 111 may also be directly coupled to any of the networks, in oneembodiment.

A peripheral 120 or series of peripherals 120, e.g., facsimile machines,printers, networked storage units, etc., may be coupled to one or moreof the networks 104, 106, 108. It should be noted that databases,servers, and/or additional components may be utilized with, orintegrated into, any type of network element coupled to the networks104, 106, 108. In the context of the present description, a networkelement may refer to any component of a network.

FIG. 2 shows a representative hardware environment associated with auser device 116 and/or server 114 of FIG. 1, in accordance with oneembodiment. Such figure illustrates a typical hardware configuration ofa workstation having a central processing unit 210, such as amicroprocessor, and a number of other units interconnected via a systembus 212.

The workstation shown in FIG. 2 includes a Random Access Memory (RAM)214, Read Only Memory (ROM) 216, an I/O adapter 218 for connectingperipheral devices such as disk storage units 220 to the bus 212, a userinterface adapter 222 for connecting a keyboard 224, a mouse 226, aspeaker 228, a microphone 232, and/or other user interface devices suchas a touch screen and a digital camera (not shown) to the bus 212,communication adapter 234 for connecting the workstation to acommunication network 235 (e.g., a data processing network) and adisplay adapter 236 for connecting the bus 212 to a display device 238.

The workstation may have resident thereon an operating system such asthe Microsoft Windows® Operating System (OS), a MAC OS, or UNIXoperating system. It will be appreciated that a preferred embodiment mayalso be implemented on platforms and operating systems other than thosementioned. A preferred embodiment may be written using JAVA, XML, C,and/or C++ language, or other programming languages, along with anobject oriented programming methodology. Object oriented programming(OOP), which has become increasingly used to develop complexapplications, may be used.

In existing tape formats, a single host, which may be any type ofcomputing device or application, writes to the tape one wrap at a time.A wrap is a collection of related tracks that are written or readsimultaneously by a tape drive head. A tape drive head has several readelements and write elements, which may be present on a single ormultiple modules. A track is the data written by a single write elementand read by a single read element. For example, a 16-channel headtypically has 16 write elements and 16 read elements associated witheach travel direction. During a write, the head may write 16 tracks inparallel. During a read, the head may read 16 tracks in parallel. Thegroup of 16 simultaneously accessed tracks comprises a wrap.

EMBODIMENTS

According to some embodiments, a method to mitigate the TDS factor byreducing the overall track spacing of each write and read pass of thehead on the tape is described. This is accomplished, in some approaches,by introducing a new tape servo format, a new data track pattern, a newread/write head, and/or a new write, read, and servo method. These newintroductions allow the TDS value to be significantly reduced, and insome approaches cut about in half, and thus relieves the TMR budget onthe magnetic tape so that the track spacing can be reduced allowing formore tracks, thereby increasing the capacity on the magnetic tapecartridge. The TDS portion of the TMR budget is typically 15% to 20% oftape capacity and without the reduction, it consumes a larger portion astrack density on the magnetic tape increases.

A new servo format is proposed herein, and has a shorter servo patternheight, increased servo pattern stripe angle, and scaled stripe widthand spacing to improve the sampling rates with minimum changes tocurrent electronics and code. This new pattern allows for more spacebetween servo patterns to place data tracks and higher resolutiontrack-following servo control. This is done, in one approach, byreducing the servo pattern height from 186 μm to 93 μm, in addition tomodifying other key parameters.

Now referring to FIG. 3, according to one embodiment, several newdimensions are presented. The magnetic tape 304 travels in the directionindicated near the bottom of the tape 304, and the magnetic head 302 ispositioned as shown. One new servo format parameter is a servo bandheight a of between about 80 μm and about 120 μm, such as about 93 μm.Some other new servo parameters include a servo stripe angle θ ofbetween about 10° and about 25°, such as about 12°; a stripe width γ ofbetween about 1.0 μm and about 2.2 μm, such as about 1.26 μm; and aservo frame length δ of between about 120 μm and about 180 μm, such asabout 152 μm. The servo band pitch β may be determined based on the datatrack width. A preferred about 12° stripe angle θ provides greaterpositional resolution on the servo pattern that can increase the numberof tracks, according to some embodiments. The changes to the stripewidth γ and pattern length δ allow for improved sampling rate of theservo pattern, according to some approaches.

In Linear Tape Open (LTO), the adjacent servo patterns are shifted inthe longitudinal directions to enable detecting which databand is beingaccessed. In some approaches, such as the 3592 format, the databandinformation may be written into the LPOS data. This new servo formatallows either method to be used at the time of servo writing. However,it is felt that the encode method is more reliable and preferable.

This new servo format also allows for different head configurations. Forexample, a 32 track head 400 can be used to increase the data rate onthe media. This head 400 is illustrated in FIG. 4. This method,according to some approaches, may be configured to be backwardcompatible with either previous LTO or 3592 formats. In someembodiments, the format may be used with a new 16 track head 500 that isshown in FIG. 5, in one embodiment. This head may be configured to have16 write tracks adjacent to 16 read tracks, in one embodiment. Thisallows for a symmetric head design where both the left and right sidemodules can be produced from identical parts, which are inverted withrespect to each other in the final product. One write procedure mayinclude writing using the upper 16 tracks on the right side module whilereading with the upper 16 tracks on the left side module, in oneembodiment. During the forward write operation the upper right sideservo head may be used to control track position with the bottom servoserving as the backup element should the top head signal become invalid.In the reverse direction, the bottom 16 write tracks of the left sidemodule may be used to write while the bottom 16 read tracks may be usedto read/verify. In addition, the bottom left side servo head may be usedfor tracking with the top left side being used if the bottom signal isinvalid.

One advantage to this method is that the head positions relative to theservo pattern do not change between forward and reverse directions,according to some approaches. This head's format may not be compatiblewith existing LTO formats in some embodiments. This new 16 track headand new servo format provide a reduced head span and servo to readerspan that reduces the TDS component by up to slightly more than 50%.This allows for increased track density as the various tape drivegenerations are developed. This new 16 track scheme also allows forreduced head complexity and cost and reduced channel electronicscomplexity and cost.

In addition to the reduced track span, the servo control code can alsobe implemented to better position the read heads over data. For example,from the 16 track discussion above, if the servo element that isfarthest away from the write heads is used during the write or readprocess, there could be a larger TDS component introduced in the written(or read) track positions due to the larger servo to reader spacing, insome embodiments. If so, then during reading, the servo may be adjustedthrough an algorithm to offset the head in the direction that improvesthe read quality of the data tracks. This may be accomplished byadjusting tracking position with an offset that is generated frommonitoring the error rate of the top most (track 0) and bottom most(track 15) read error rate so that they are minimized relative to eachother.

According to some preferred embodiments, a magnetic recording tapeincludes a plurality of servo tracks, each servo track comprising aseries of magnetically defined bars having an average height of betweenabout 80 microns and about 120 microns, where “about X microns” as usedherein indicates X microns±10%. For example, about 80 microns indicates80 microns±8 microns. In addition, an average stripe angle of the barsis between about 10° and about 25°, where “about X°” indicates X°±5%.For example, about 10° as used herein indicates 10°±0.5°. A stripe angleis measured between a longitudinal axis of each respective bar and aline oriented perpendicular to a direction of tape travel and parallelto a plane of the tape. Also, an average stripe width of the bars asmeasured perpendicular to the axis of each respective bar is betweenabout 1.0 micron and about 2.2 microns, and an average servo framelength of groups of the bars comprising a servo frame is between about120 microns and about 180 microns.

In some approaches, the various dimensions recited above may be slightlynarrowed to gain further advantages over conventional systems andmagnetic tapes. For example, an average height of the bars may bebetween about 90 microns and about 95 microns, the average stripe angleof the bars may be between about 11° and about 13°, the average stripewidth of the bars may be between about 1.1 microns and about 1.4microns, and the average servo frame length of groups of the barscomprising a servo frame may be between about 140 microns and about 160microns.

In another preferred embodiment, a magnetic recording tape includes aplurality of servo tracks, each servo track comprising a series ofmagnetically defined bars having an average height of about 93 micronsand an average stripe angle of the bars is about 12°. A stripe angle ismeasured between a longitudinal axis of each respective bar and a lineoriented perpendicular to a direction of tape travel and parallel to aplane of the tape. Also, an average stripe width of the bars as measuredperpendicular to the axis of each respective bar is about 1.26 microns,and an average servo frame length of groups of the bars comprising aservo frame is about 152 microns.

According to another embodiment, a magnetic recording tape includes aplurality of servo tracks, each servo track comprising a series ofmagnetically defined bars having an average height of between about 90microns and about 95 microns, and an average stripe angle of the bars isbetween about 11° and about 13°. Also, an average stripe width of thebars is between about 1.1 microns and about 1.4 microns, and an averageservo frame length of groups of the bars comprising a servo frame isbetween about 140 microns and about 160 microns.

Moreover, in some approaches, the average height of the bars may beabout 93 microns, and the average stripe angle of the bars may be about12°.

In further approaches, the average stripe width of the bars may be about1.26 microns, and the average servo frame length of groups of the barscomprising a servo frame may be about 152 microns.

In another embodiment, a system includes a head, such as a magnetic head(e.g., tunneling magnetoresistance (TMR) effect head, giantmagnetoresistance (GMR) effect head, etc.), having at least one servoreader and a linearly-oriented array of data transducers. The datatransducers are of a type selected from a group consisting of: readersand writers, i.e., at least some of the data transducers are eitherreaders or writers. In addition, a controller is operative toselectively enable every other transducer of a particular type in thearray in a first mode of operation (reading and/or writing, e.g.,format), and the controller is operative to selectively enable everytransducer of the particular type in the array in a second mode ofoperation. For example, the controller may have two modes of operation.In the first mode, every other transducer may be operated to write orread. In the second mode, the controller may selectively operate eachtransducer to write or read.

In some approaches, the array may include writers, where every otherwriter in the array may be activated in the first mode of operation, andevery writer in the array may be activated in the second mode ofoperation. Further, the head may include a linearly-oriented secondarray of readers, where every other reader in the second array may beactivated in the first mode of operation, and every reader in the secondarray may be activated in the second mode of operation. This allowsread-while-write operation of the head in both modes.

In more approaches, the array may include readers, where every otherreader in the array may be activated in the first mode of operation, andevery reader in the second array may be activated in the second mode ofoperation.

In more approaches, the first mode of operation may correspond to afirst tape format and the second mode of operation may correspond to asecond tape format.

In another embodiment, a system includes a head having at least oneservo reader and a linearly-oriented array of data transducers. The datatransducers are selected from a group consisting of readers and writers.Also, the system includes a switch operative to selectively enable everyother transducer of a particular type in the array in a first mode ofoperation (reading and/or writing, e.g., format), and the switch is alsooperative to selectively enable every transducer of the particular typein the array in a second mode of operation. The switch may be in thehead, in a cable coupled to the system, on a circuit board, etc.

According to some approaches, the array may include writers, where everyother writer in the array may be activated in the first mode ofoperation, and every writer in the array may be activated in the secondmode of operation. In further approaches, the head may include alinearly-oriented second array of readers, where every other reader inthe second array may be activated in the first mode of operation, andevery reader in the second array may be activated in the second mode ofoperation. This allows read while write in both modes.

In more approaches, the array may include readers, where every otherreader in the array may be activated in the first mode of operation, andevery reader in the second array may be activated in the second mode ofoperation.

According to some embodiments, the first mode of operation maycorrespond to a first tape format and the second mode of operation maycorrespond to a second tape format, thereby allowing the system to writeand/or read to/from more than one magnetic tape format, which may allowfor backward compatibility with conventional tape formats and devices.

In another preferred embodiment, a servo format for a magnetic tapecomprises at least two servo tracks written to the magnetic tape, the atleast two servo tracks comprising a set of magnetically defined bars.The magnetically defined bars have an average height of between about 80microns and about 120 microns, an average stripe angle of the bars beingmeasured between a longitudinal axis of each respective bar and a lineoriented perpendicular to a direction of tape travel and parallel to aplane of the tape of between about 10° and about 25°, an average stripewidth of the bars of between about 1.0 micron and about 2.2 microns, andan average servo frame length of groups of the bars comprising a servoframe of between about 120 microns and about 180 microns.

Of course, any of the embodiments and approaches, described above may beincluded in the description of the servo tape format.

In some embodiments, less expensive drives and/or higher data ratedrives may be produced by allowing the for a new format to support 16data tracks, which is less expensive due to lower cost, size, andcomplexity of the channel electronics, or 32 data tracks which allowsfor a 2× data rate improvement at the same tape speed.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of a preferred embodiment shouldnot be limited by any of the above-described exemplary embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

What is claimed is:
 1. A magnetic recording tape, comprising: aplurality of servo tracks, each servo track comprising a series ofmagnetically defined bars, wherein an average stripe width of the barsis between about 1.0 micron and about 2.2 microns, wherein an averageservo frame length of groups of the bars comprising a servo frame isbetween about 120 microns and about 180 microns.
 2. The magneticrecording tape as recited in claim 1, wherein the average height of thebars is between about 80 microns and about 180 microns.
 3. The magneticrecording tape as recited in claim 1, wherein an average stripe angle ofthe bars is between about 10° and about 25°.
 4. The magnetic recordingtape as recited in claim 1, wherein the average stripe width of the barsis between about 1.1 microns and about 1.4 microns.
 5. The magneticrecording tape as recited in claim 1, wherein the average servo framelength of groups of the bars comprising a servo frame is between about140 microns and about 160 microns.
 6. The magnetic recording tape asrecited in claim 1, wherein the average height of the bars is betweenabout 90 and 95 microns, wherein the average stripe angle of the bars isbetween about 11° and about 13°.
 7. The magnetic recording tape asrecited in claim 1, wherein the average stripe width of the bars isbetween about 1.1 microns and about 1.4 microns.
 8. The magneticrecording tape as recited in claim 1, wherein an average servo framelength of groups of the bars comprising a servo frame is between about140 microns and about 160 microns.
 9. A system, comprising: a headhaving at least one servo reader and an array of data transducers of atype selected from a group consisting of readers and writers; and acontroller operative to selectively enable every other transducer of aparticular type in the array in a first mode of operation, and operativeto selectively enable every transducer of the particular type in thearray in a second mode of operation.
 10. The system of claim 9, whereinthe array includes writers, every other writer in the array beingactivated in the first mode of operation, every writer in the arraybeing activated in the second mode of operation.
 11. The system of claim10, wherein the head further includes a second array of readers, everyother reader in the second array being activated in the first mode ofoperation, every reader in the second array being activated in thesecond mode of operation.
 12. The system of claim 9, wherein the arrayincludes readers, every other reader in the array being activated in thefirst mode of operation, every reader in the second array beingactivated in the second mode of operation.
 13. The system of claim 9,wherein the first mode of operation corresponds to a first tape formatand the second mode of operation corresponds to a second tape format.14. The system of claim 9, further comprising a switch operative toselectively enable every other transducer of the particular type in thearray in the first mode of operation, and operative to selectivelyenable every transducer of the particular type in the array in thesecond mode of operation.
 15. A method for writing and/or reading dataon a magnetic tape, the method comprising: reading at least one of aplurality of servo tracks on the magnetic tape, the servo tracks eachcomprising a set of magnetically defined bars, the magnetically definedbars having: an average stripe width of the bars of between about 1.0micron and about 2.2 microns; and an average servo frame length ofgroups of the bars comprising a servo frame of between about 120 micronsand about 180 microns.
 16. The method of claim 15, wherein the averageheight of the bars is between about 80 microns and about 180 microns.17. The method of claim 15, wherein an average stripe angle of the barsis between about 10° and about 25°.
 18. The method of claim 15, whereinthe average stripe width of the bars is between about 1.1 microns andabout 1.4 microns.
 19. The method of claim 15, wherein the average servoframe length of groups of the bars comprising a servo frame is betweenabout 140 microns and about 160 microns.
 20. The method of claim 15,wherein the average height of the bars is between about 90 and 95microns, wherein the average stripe angle of the bars is between about11° and about 13°.